Define manifest for .NET SDK (#120)

* Define manifest for .NET SDK 3.1.202

* Remove invalid log property

* Remove comment out unupported ManifestVersion property

manifests/Microsoft/dotnet/3.1.202.yaml

@@ -0,0 +1,22 @@
+Id: Microsoft.dotnet
+Publisher: Microsoft
+Name: .NET Core
+AppMoniker: dotnet
+Version: 3.1.202
+License: MIT
+LicenseUrl: https://github.com/dotnet/core/blob/master/LICENSE.TXT
+MinOSVersion: 6.1.7601
+Description: .NET Core is an open-source, general-purpose development platform. You can create .NET Core apps for Windows, macOS, and Linux for x64, x86, ARM32, and ARM64 processors using multiple programming languages. Frameworks and APIs are provided for cloud, IoT, client UI, and machine learning.
+Homepage: https://docs.microsoft.com/dotnet/core/
+Tags: .NET, .NET Core, dotnet, C#, csharp, F#, fsharp, VB, Visual Basic
+Commands: dotnet
+InstallerType: exe
+Installers:
+  - Arch: x64
+    Url: https://download.visualstudio.microsoft.com/download/pr/f222bff9-8f0a-4720-b9db-7f80c31c6561/5d522c84f2715df94f7a988d8ab547b8/dotnet-sdk-3.1.202-win-x64.exe
+    Sha256: 3bec85a0ad861d9cb0ab8dccc0a6870aca3189c1343f7db55d42f353b33fb65e
+    Switches:
+      Custom: /install
+      Silent: /quiet
+      SilentWithProgress: /passive
+# ManifestVersion: 0.1.0